Muy also admitted to gang and great bodily injury enhancements and an additional gang charge, receiving 19 years and eight months in state prison.

Authorities believe Muy drove the gang to Panella Park, where Rin Ros was on Aug. 6, 2010. The group, who considered Ros a "buster" for wanting out of their Southeast Asian gang, stomped the teen to death in a ritual beating to eliminate his membership, authorities have said.

One co-defendant said Muy was the first to throw a punch.

During police interrogation, co-defendant Kailler Sam, 17, said the gang didn't mean to kill Ros and called his death an accident.

"Everything just got out of control," Sam said.

The San Joaquin County district attorney has prosecuted eight individuals, five of them juveniles charged as adults.

Sam and three others - Ron Korm, 18; Ly Jan So, 26; and Allen Phalit, 18 - have also accepted the same deal made as Muy, avoiding potential life sentences.

Phalit took the agreement after reneging on another deal that required him to cooperate.

Another defendant, 23-year-old Savann Rang, opted to go to trial and was recently convicted by a jury of second-degree murder.

Rang's sentencing, scheduled for Tuesday, was continued to Aug. 5. He faces 25 years to life in prison for murder with enhancements and an additional eight months for a gang charge.

Still awaiting trial are two 17-year-old defendants, Jereme Sin and Sovannara Yam, held in juvenile hall. They are expected to be tried together.

Prosecutor Tori Verber-Salazar declined to comment Tuesday because of the pending cases.